Minimally invasive surgery (MIS) is a modern surgical technique in which operations in the abdomen and thorax or elsewhere are performed through small incisions in the skin. Since 1981, when the first laparoscopic cholecystectomy (gallbladder removal) was performed, this surgical field has greatly improved due to various technological advances. Today this operation typically uses 3-6 abdominal skin incisions (each approximately 5-12 mm in length), through which optical fibers, cameras, and long operating instruments are inserted into the abdominal cavity. The abdomen is usually insufflated (inflated) with carbon dioxide gas to create a working and viewing space and the operation is performed using these long instruments through the incisions, images acquired by way of one or more camera devices inserted into the working and viewing space are viewed on a TV monitor beside the patient as the surgery progresses.
One currently available camera for MIS is composed of a 12-15-inch long tube containing several lenses and optical fibers (the laparoscope). The front section of the laparoscope enters the abdomen through a portal called a “trocar” and the back end is connected to a power source, light source and supporting hardware through large cables protruding from the rear of the scope. The internal optical fibers convey xenon or halogen light via an external light source into the internal cavity and the lenses transfer the images from within the cavity to an externally connected portable video camera. Disadvantages of this imaging device include its two-dimensional view, lack of sufficient optical zoom, inability to adjust its angle of view or angle of illumination without a new incision, inability to control light intensity, and restrictions on its movement due to its large size and external cables. This is especially significant in this era of MIS in which it is desired to minimize the number and extent of incisions, and wherein new technologies are being developed such as Natural Orifice Translumenal Endoscopic Surgery (NOTES) which use no abdominal incisions at all, but instead utilize a single trocar inserted into the mouth or vagina to carry all surgical instruments as well as the camera and light source.
Lighting has been a challenge for laparoscopic cameras because they operate in an environment of extreme darkness where accessibility to sources of illumination is limited. Further, new cameras are being utilized which possess features such as a flexible field of view or optical zoom capability. Although such camera features are extremely desirable insofar as they allow surgeons to obtain both the global and the detailed view of the patient's abdomen as well as a large working space to practice surgery, it results in more strict requirements on lighting.
More particularly, current light sources including halogen and LED lamps are designed to have a fixed radiation pattern characterized by a full-width half intensity angle. For those cameras for which zoom is an option, when a surgeon wants to see the details of an organ in a zoom-in mode, the angle of illumination may be much greater than the camera's field-of-view and thus there is often insufficient lighting for the desired image resulting in poor quality of the acquired image. On the other hand, when a surgeon operates the camera in zoom-out mode to achieve a wide field-of-view, the limited illumination angle of the light source may not cover the entire desired image area, leading to rapid fading of the acquired image towards the edge of the image field. In addition, the center portion of the acquired image may be over illuminated and saturated, resulting in penalty in resolution and dynamic range.
For at least the above-described reasons, therefore, it would be advantageous if an improved system and method for illumination capable of being employed along with cameras as are used in a variety of applications including, for example MIS applications, could be developed.
Further, images corresponding to one or more color channels of the camera can be blurred, and it would be advantageous if an improved deblurring method could be developed to provide enhanced image quality.